Design of Single-Stage Resonant Converters Using Piezoelectric Transformer for Driving LED

• Main Authors: Po-Hsun Chen, 陳博勳
• Other Authors: Tsao-Tsung Ma
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/34994367661622805206

碩士 === 國立聯合大學 === 電機工程學系碩士班 === 99 === This thesis investigates steady-state electrical characteristics of piezoelectric elements under temperature variations and presents a design procedure of a high-frequency power converter based on piezoelectric transformers for driving light-emitting diodes (LED). Investigations on steady-state responses of piezoelectric elements include piezoelectric transformers and piezoelectric actuators. In this thesis, a set of modified parameters in conventional equivalent circuit of piezoelectric transformers has been derived with the help of experimental studies. The effectiveness of the equivalent circuit with the derived parameters has been verified with results from simulations and practical measurements. In the aspects of designing LED driving circuit on piezoelectric transformers, the basic features of LED driving with AC source are first addressed. Then, a high-frequency power converter based on piezoelectric transformers is designed for driving LED. The proposed high-frequency converter composed of a half-bridge topology and a piezoelectric transformer has a number of advantages; i.e. intrinsic over current protection, lower electric magnetic interferences (EMI) and the current sharing problem in sets of anti-parallel LED array can be solved easily. Considering the requirements in practical applications, issues regarding the improvement of power factor, the elimination of effects of temperature on LED currents have been investigated.